1. Field of the Invention
This invention relates generally to the in situ machining of the main bearing housings of large internal combustion engines, turbine casings, bearing housings of reduction gears, stern tubes and stern bearings of ships, and other large pieces of machinery which cannot be transported practically to machine shops for repairs.
2. Brief Description of Background Art
A number of apparatus for commercially available for in situ refinishing of the surfaces of the main bearing housings of very large internal combustion engines or other large machine elements which require line boring in place. In these engines a plurality of thin insert shell or ball bearings are situated in axially spaced alignment along the length of the shafts or a crankshaft main journals. These plain shells or other types of bearings rest inside the bearing housings to carry shafts or crankshafts rotating at high speeds with high loads.
A boring bar is inserted into the bearing housings after the crankshaft or other rotating element has been removed from the bedplate or casing. Because of the great size of these engines, the boring bar may be on the order of 30 feet or longer in length. Apparatus of this kind may be utilized in reboring, in situ, the main bearing housings, turbine casings, turbine bearing housings of diesel marine engines, reduction gear casings, stern tubes of ships and other large scale machine parts. Because of their large size, transportation of these parts to a machine shop may be impractical.
Conventionally in such devices a boring bar is rotated from an exterior position. The boring bar carries one boring element which extends radially from the boring bar to refinish the bearing housing surface as the boring bar is rotated. Since the boring bar may be positioned within the bedplate, the boring element may be repositioned to successively bore different bearing housings in a sequential fashion without repositioning the boring bar.
However with conventional commercially available devices it is sometimes very difficult to align the boring bar with respect to the bearings to be refinished. Specifically it is very difficult to alter the inclination of the boring bar with respect to the bearing housings so that an exact alignment is achieved. This may result in misalignment of the boring bars, excessive boring, or excessive time consumption in attempting to refinish a given machine.